Myxococcus xanthus is an excellent prokaryotic system for the study of the regulation of development. M. xanthus show a developmental cycle which is similar to the eukaryotic slime molds such as Dictyostelium discoideum. However, there are several distinct advantages to study of development of M. xanthus, since it is a simple gram-negative bacterium. We propose to study morphogenesis and the molecular mechanism of control of gene expression during development using M. xanthus as a model system. Particularly we first attempt to focus our effort on protein S, protein T and protein U, which are three representative development-specific proteins. Protein S and U have aleady been purified homogeneity (protein S has been crystalized). We will determine their primary structures as well as their secondary structures. We will also investigate biochemically and genetically their functions in morphogenesis of M. xanthus. We will attempt to determine the molecular mechanism for transport of proteins S and U from the cytoplasm to the spore-surface. Using radioactive anti-sera against these proteins, we will clone the genes for these proteins into vectors carrying E. coli promotors such as lac promotor and 1pp promotor. These clones will be characterized biochemically and will be used as probes to examine the regulatory mechanism for gene expression during development.